Determinants of hospital readmissions in older people with dementia: a narrative review

Introduction Over 50% of hospitalised older people with dementia have multimorbidity, and are at an increased risk of hospital readmissions within 30 days of their discharge. Between 20-40% of these readmissions may be preventable. Current research focuses on the physical causes of hospital readmissions. However, older people with dementia have additional psychosocial factors that are likely to increase their risk of readmissions. This narrative review aimed to identify psychosocial determinants of hospital readmissions, within the context of known physical factors. Methods Electronic databases MEDLINE, EMBASE, CINAHL and PsychInfo were searched from inception until July 2022 and followed up in February 2024. Quantitative and qualitative studies in English including adults aged 65 years and over with dementia, their care workers and informal carers were considered if they investigated hospital readmissions. An inductive approach was adopted to map the determinants of readmissions. Identified themes were described as narrative categories. Results Seventeen studies including 7,194,878 participants met our inclusion criteria from a total of 6369 articles. Sixteen quantitative studies included observational cohort and randomised controlled trial designs, and one study was qualitative. Ten studies were based in the USA, and one study each from Taiwan, Australia, Canada, Sweden, Japan, Denmark, and The Netherlands. Large hospital and insurance records provided data on over 2 million patients in one American study. Physical determinants included reduced mobility and accumulation of long-term conditions. Psychosocial determinants included inadequate hospital discharge planning, limited interdisciplinary collaboration, socioeconomic inequalities among ethnic minorities, and behavioural and psychological symptoms. Other important psychosocial factors such as loneliness, poverty and mental well-being, were not included in the studies. Conclusion Poorly defined roles and responsibilities of health and social care professionals and poor communication during care transitions, increase the risk of readmission in older people with dementia. These identified psychosocial determinants are likely to significantly contribute to readmissions. However, future research should focus on the understanding of the interaction between a host of psychosocial and physical determinants, and multidisciplinary interventions across care settings to reduce hospital readmissions. Supplementary Information The online version contains supplementary material available at 10.1186/s12877-024-04905-6.


Background
Dementia is a known public health priority due to the increasing amount of people living with the condition worldwide and the subsequent demands placed on health and social care systems, the economy and society [1].The World Alzheimer's Report estimated that over 46 million people were living with dementia worldwide in 2015, and this figure is estimated to increase to 131.5 million by 2050 [2].In the United Kingdom, there are currently over 910,000 people living with dementia (PLWD), and this number is projected to increase to over 2 million by 2051, with dementia care costs estimated to have an overall economic impact of £26 billion per annum [3,4].Dementia has a complex relationship with long-term conditions, with adverse impacts on older PLWD [5].This health and social care challenge is demonstrated by UK Hospital Episode Statistics (HES) data in research by Age UK and the National Institute for Health and Care Research (NIHR), where 53% of hospitalised PLWD have three or more long-term conditions [6].Additionally, the negative impact of psychosocial factors such as social isolation, poor dementia-friendly environments and behavioural and psychological symptoms of dementia (BPSD), may also contribute towards increased hospital readmissions in PLWD.People with dementia who live in areas of social and economic deprivation or live with depression or anxiety, are at a greater risk of avoidable healthcare outcomes including hospital readmissions [7,8].Recurrent admissions could lead to faster deterioration, poor quality of life and increased mortality risk for PLWD [9].
Analysis from the UK HES data commissioned by Alzheimer's Research UK, found that the number of PLWD aged 65 and over being admitted into hospitals increased by 93% from 210,000 admissions in 2010/11 to 405,000 in 2017/18 [10].These hospitalisations could be related to the increased severity of long-term conditions, care needs at the point of discharge, and inadequate resources in post-discharge care [11].These figures escalate pressure on healthcare services in caring for PLWD.Additionally, analysis of NHS data by the Alzheimer's Society found that older people with dementia remain in hospital for up to seven times longer than their age-matched groups without dementia [12].
Hospital readmission in older adults is recognised as an unplanned return admission to an acute care hospital, within 30 days of their previous admission [13,14].International research studies indicate that PLWD are more likely to be readmitted to hospital within 30 days of their index admission, where 20-40% of these readmissions are avoidable [11,[15][16][17].Previous literature reviews focused on the physical determinants of hospital readmissions, such as multimorbidity [16,18,19].However, PLWD also require support with their psychosocial needs in addition to their physical needs.Throughout the dementia trajectory, biomedical deterioration such as frailty and multimorbidity progress in conjunction with psychosocial deterioration, including depression and poor social support [20].Cohen-Mansfield [21] proposed one of the first biopsychosocial models of dementia, where dementia manifests from predisposing factors, life-long events and current biological, psychological and environmental factors.It was suggested that these factors affect the trajectory of dementia through cognitive, behavioural, self-maintenance and affective functioning.For example, pain is a common physical condition with psychosocial impact on cognitive, behavioural and affective functioning for PLWD [22].Spector and Orrell [23] adapted the biopsychosocial model of dementia, where they proposed the impact of biopsychosocial factors varying along the dementia trajectory from normal ageing to the end of life.Hence, the same biopsychosocial factors may have different effects depending on the cognitive status of PLWD [23].This is evident as hospital readmissions have been found to increase towards the end of life for PLWD, with various factors including poor community support, pain and multimorbidity [24].Therefore, focusing on a few factors for hospital readmissions is problematic, as the dementia trajectory and health outcomes for PLWD are based on the interaction of a myriad of biomedical and psychosocial determinants [25].Understanding the psychosocial determinants of hospital readmissions in PLWD may provide individual benefits as well as service implications in reducing this problem.
This narrative review aims to identify the psychosocial determinants of hospital readmissions in older PLWD, within the context of the known physical determinants.

Methods
A review was conducted to develop a holistic understanding of the determinants of hospital readmissions among older PLWD.The methodology of this review followed the framework outlined by Arksey and O'Malley [26].The reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR), to provide a scientific approach to this review [27].A protocol was registered with the Zenodo repository (DOI number: https:// doi.org/ 10. 5281/ zenodo.10044 172).

Step one: identifying the research question
This narrative review was guided by the following research question: What are the psychosocial determinants for acute hospital readmissions for older people with dementia, within 30 days of an index admission?
Step two: identifying relevant studies A defined search strategy was used for the electronic databases MEDLINE, EMBASE, CINAHL and PsychInfo, which were searched from inception to July 2022.A follow-up search of the electronic databases was carried out in February 2024, to retrieve the latest publications.Search terms for dementia and hospital readmissions were used in combination with truncation and Boolean operators, including AND and OR, to yield results.The search terms used were followed by the dementia literature search strategies guidance, by the National Institute for Health and Care Excellence (NICE) [28].To ensure that further relevant articles were identified within the search, the citations of all included studies were searched and screened for inclusion.An initial pilot search was conducted in June 2022, to refine the search strategy and ensure that the search terms produced relevant results.This technique was used to ensure that the search was specific enough to answer the research question, and broad enough to obtain the relevant literature, including non-psychological determinants for readmissions.No restrictions were placed on the publication year.The full search applied to the MEDLINE database is outlined in supplementary data 1.
Step three: study selection Publications were included in the review if they involved: -Adults aged 65 years and over living with a dementia diagnosis.-Health and social care workers who work in dementia care, within hospital and community settings.-Family carers of people with dementia who have experienced hospital readmissions.-All empirical studies including quantitative and qualitative research.
Publications were excluded for the following reasons: -Hospital readmissions that do not include people with dementia.-Adults aged under 65 years living with dementia.
-Conference abstracts, theses, editorials and opinion pieces.-Articles not in English language.
All publications retrieved from the search strategy were imported into Endnote 20 software to remove duplications and manage references.All titles and abstracts were screened against the eligibility criteria by two independent reviewers (BB and NT).Eligible titles and abstracts then had full-text screening against the eligibility criteria, by the two independent reviewers (BB and NT).Where there was any disagreement among the reviewers, one reviewer (BB) re-read the full-text publication against the eligibility criteria and a consensus was reached by the reviewers.
Step four: charting the data A data extraction form was developed on Microsoft Excel and pilot-tested on five publications by random selection, to ensure that the relevant data were extracted from the publications.Details on the data extraction form for included publications included study title, author and year, country, study design and aim, research setting, data source, study period, sample characteristics, readmission measure and rate, and reasons for hospital readmissions (Table 1).One reviewer (BB) completed the data extraction for all included publications, which was reviewed and discussed with a second reviewer (NT), for overall agreement of data extraction.

Step five: collating, summarising, and reporting the results
The data were cross-tabulated and compiled on a spreadsheet in Microsoft Excel for narrative synthesis to be conducted.As the measurements of the determinants of hospital readmissions in older PLWD were variable such as all-cause 30 and 180-day readmission rates, frequencies of rehospitalisations and successful dischargeto-community rates, methods of statistical pooling data were not feasible.
A narrative synthesis approach was used to allow the integration of quantitative and qualitative data, to identify patterns related to hospital readmissions in older PLWD.Two elements of narrative synthesis outlined by Popay et al. [29] were adopted.The two elements used were 'developing a preliminary synthesis' and 'exploring relationships in the data'.The elements 'developing a theory of how and why interventions work' and 'assessing the robustness of the synthesis' were not used, as this narrative review was exploratory in nature and assessing the quality of studies was not required to map the relevant evidence available.The summarising of data was completed by one reviewer (BB) and discussed further with a second reviewer (NT), to gain agreement on the developed narrative categories and to report the findings.

Summary of results
The search strategy yielded 4757 articles.After duplicates were removed and the inclusion of five additional studies from citation searching, 4736 titles and abstracts were screened.Thirty articles underwent full-text screening, and fourteen studies were excluded because they did not meet the inclusion criteria.Reasons for exclusion included the age of people with dementia being as young as 30 years old [30], a study based on hospital discharge issues with no relation to hospital readmissions [31], studies investigating initial hospitalisations instead of recurrent admissions [7,24,[32][33][34][35][36][37], and the research being published as PhD theses [38,39].The full-text versions of two articles could not be located [40,41].After the follow-up search, 1633 titles and abstracts were screened.Three articles underwent full-text screening.Among this subgroup, two studies did not meet the inclusion criteria as they included PLWD aged under 65 years old [42,43].
In total, 17 articles were included in this review.A flow chart of the screened studies is shown in Fig. 1.

Inadequate hospital discharge planning
Five studies highlighted patterns of inadequate hospital discharge planning in older PLWD, where 30-day hospital readmission rates increased when older adults were discharged to live at home alone or after short-term domiciliary care [16,45,46,50,52].The studies by Knox et al. [46] and Callahan et al. [50] identified that the primary reasons for unsuccessful discharges were due to unplanned hospital readmissions during and following domiciliary care, where PLWD were living at home alone.Tropea et al. [52] demonstrated similar results, where their cohort study identified increased 2, 7 and 28-day hospital readmission rates when people with dementia were discharged to their homes.This increase in hospital readmission rates resulted in a 47% increase in healthcare utilisation costs, compared to hospital readmissions among older people without cognitive impairment [52].In a study where discharge plans developed by social workers were assessed for adequacy by primary care providers, Cummings et al. [45] identified factors that predicted hospital readmission for PLWD.Inadequate discharge plans included factors related to complex care (p < 0.01), problematic behaviours (p < 0.05), unrealistic family beliefs in the ability to provide care (p < 0.001), and unavailable resources (p < 0.01) [45].In addition, research conducted by Graversen et al. [16] compared the risk of 30-day hospital readmission after a hospital discharge for pneumonia in PLWD and people without dementia.Graversen et al. [16] identified a 7% increase in hospital readmissions for PLWD compared to people without dementia, corresponding to an overall adjusted incidence rate ratio (aIRR) of 1.07 (95% CI 1.04-1.10).The highest hospital readmission rates were found within the first few days of hospital discharge for PLWD hospitalised with pneumonia [16].The short time spent at home before hospital readmissions suggests inadequate hospital factors for PLWD, which include a lack of dementia-friendly hospital environments and poorly updated discharge planning [16].

Interdisciplinary collaboration
Three studies [17,55,56] highlighted contrasting examples of interdisciplinary collaboration between healthcare staff and older PLWD, which could act as a facilitator or barrier towards hospital readmissions in dementia.Gilmore-Bykovskyi et al. [55] interviewed nursing home staff about the needs of PLWD during hospital-to-nursing home transitions.Nursing home staff reported feeling ill-equipped with inadequate information sharing from hospital ward staff, short discharge timeframes, and limited control over nursing home admission discussions regarding the individuals' care needs [55].The nursing home staff acknowledged that hospital and nursing home staff may have different perceptions of the physical and psychosocial care needs for PLWD, such that these differences may contribute towards increased hospital readmissions [55].
As a corollary, a randomised controlled trial by Gustafsson et al. [56] examined whether clinical pharmacist participation in hospital ward rounds would reduce drug-related hospital readmission rates in PLWD.In the intervention group, the 30-day and 180-day hospital readmission rates were 5% and 11% compared to the control group readmission rates of 11% and 20%, when adjusted for patients with heart failure [56].It was thought that such reduced drug-related hospital readmissions in PLWD were due to the close collaboration between the pharmacists and hospital ward medical team, where both areas of expertise worked together to reduce the occurrence of avoidable drug-related hospital readmissions [56].
Godard-Sebillotte et al. [17] also demonstrated adequate interdisciplinary collaboration as a key factor in reducing readmission, where they estimated the association between primary care continuity and avoidable hospital readmissions in PLWD.The results identified that when PLWD and their family carers attended regular primary care visits with the same physician, there was a reduced risk of 30-day hospital readmissions within the following year for PLWD (RR = 0.81; 95% CI 0.72-0.92;p < 0.001) [17].

Ethnic differences in dementia
An American cohort study by Gilmore-Bykovskyi et al. [57] examined the association between race and 30-day hospital readmissions among Medicare beneficiaries of Black and Non-Hispanic White individuals with dementia.The unadjusted analysis demonstrated that the odds of hospital readmission among Black beneficiaries were 37% greater compared to non-Hispanic White beneficiaries (OR 1.37, CI 1.35-1.39)[57].Disability among Black beneficiaries was twice as high compared to the disability among non-Hispanic White beneficiaries, and a disproportionate number of Black beneficiaries lived in the most disadvantaged neighbourhoods across the USA (28.6% Black vs. 8.9% non-Hispanic White) [57].After adjusting for all measured factors which included but were not limited to neighbourhood disadvantage, education level and long-term conditions, Black beneficiaries remained to have greater odds of hospital readmissions by 16% (OR 1.16, CI 1.14-1.17)[57].Gilmore-Bykovskyi et al. [57] recognised the reduction of hospital readmission odds from 37% to 16% among Black beneficiaries, indicating that approximately 50% of the observed excess risk was attributable to exposures associated with racial differences that may include unmeasured clinical factors.

Behavioural and psychological symptoms
A cohort study conducted by Tannenbaum et al. [54] investigated the association of clinical outcomes with behavioural symptoms including wandering, agitation, aggression and psychosis in hospitalised PLWD.Within the cohort of hospitalised PLWD, 40.6% had behavioural symptoms [54].Among this subgroup, 43.1% received a documented diagnosis of delirium, and 30.9% were prescribed antipsychotic medication [54].Notably, only 0.2% of PLWD with behavioural symptoms had a formal diagnosis of 'dementia with behavioural symptoms' recorded in their medical notes.Tannenbaum et al. [54] observed that hospitalised PLWD exhibiting behavioural symptoms were more likely to be admitted from a care facility (26.6% vs. 23.7%,p < 0.05).This specific cohort of patients demonstrated a higher tendency for readmission to acute medical services, compared to surgical services (92.7% vs. 91%, p = 0.003).Notably, hospital factors with this group included the presence of an indwelling catheter (11.1% vs. 6%, p < 0.001), an elevated falls risk (46.7% vs. 42.3%,p < 0.002), bed alarms attached to their hospital beds (81.6% vs 77.4%, p < 0.001), and Do Not Resuscitate (DNR) orders (40.6% vs 33.1%, p < 0.001) [54].As a result, this study concluded that hospitalised PLWD with behavioural symptoms exhibited a moderate

Interdisciplinary collaboration
Poor communication: -Poor information sharing when transitioning healthcare facilities.
-Short discharge timeframes Gilmore-Bykovskyi et al. ( 2017) [55] Good communication: -Different healthcare professionals using their expertise to achieve the same goal of reducing hospital readmissions.
-Primary care continuity between primary care professionals and PLWD and their carers.Hospitalised PLWD with behavioural symptoms

Functional ability
Individual ability to mobilise and perform selfcare tasks to reduce recurrent admissions
The frequent use of antipsychotic medication for behavioural and psychological symptoms in older PLWD may act as a determinant of hospital readmissions, which was identified in the cohort study by Daiello et al. [53].Daiello et al. [53] investigated the association of dementia with early hospital readmissions among a cohort of Medicare health insurance beneficiaries.This study highlighted that PLWD with 30-day hospital readmissions had more frequent prescriptions for antipsychotic medication, having at least two prescriptions within the study period of one year (12.7% readmission vs. 9.2% no readmission p < 0.001) [53].Additionally, frequent use of antipsychotic medication in the 6 months before or after the index hospitalisation was associated with higher odds of 30-day hospital readmissions for PLWD [53].Although not investigated in the study, Daiello and Colleagues [53] acknowledged that recurrent use of antipsychotic medication in PLWD may be a marker of unmeasured psychosocial factors including behavioural symptoms, agitation and delirium, which increases the risk of 30-day hospital readmissions.Nevertheless, this acknowledgement is supported by the results of Tannenbaum et al's study [54].

Physical determinants of hospital readmissions in dementia Functional ability
A cohort study by Knox et al. [47] outlined functional ability in PLWD as a determinant for hospital readmissions, as they examined the association between mobility, self-care and caregiver support with 30-day hospital readmissions in PLWD.The study revealed that PLWD with domiciliary care who were most dependent on mobility (OR 1.59, 95% CI 1.47-1.71)and self-care (OR 1.73, 95% CI 1.61-1.87),had the highest odds for 30-day hospital readmissions when adjusted for caregiver support [47].In the most dependent quartiles for mobility and self-care, the two most common conditions resulting in hospital readmissions were sepsis and urinary tract infections [47].This finding suggests that regardless of the level of caregiver support and dementia severity, the individuals' ability to function in the form of mobility and self-care, determines their risk of 30-day hospital readmissions.

Long-term conditions
Long-term conditions that affect PLWD were commonly listed as reasons for hospital readmissions in five studies [18,19,44,49,51].The long-term conditions included cardiovascular disease (CVD), pneumonia, urinary tract infections and falls [18,19,44,49,51].The retrospective cohort studies by Lin et al. [51] and Sakata et al. [18] retrieved similar results, where over half of the most common hospital admission reasons which included various long-term conditions, increased the hospital readmission rate for PLWD.Lin et al. [51] highlighted a 73% all-cause 30-day readmission rate, where PLWD were readmitted to hospital with different comorbidity problems from their index admission.When investigating the impact of CVD on hospital readmissions, Van de Vorst et al. [19] recognised that 37% of hospitalised PLWD and 50% of day clinic outpatients with dementia both with CVD, experienced hospital readmissions within one year.A longitudinal study by Rudolph et al. [49] demonstrated that the cumulative risk for rehospitalisation increased with the number of long-term conditions that older PLWD live with [49].The authors reported that the risk of rehospitalisation was 37% with no long-term conditions, 57% with one long-term condition, 70% with two or three long-term conditions, and 80% with four or five long-term conditions [49].However, when Chang et al. [44] explored the roles of systemic diseases and hospital admission aetiologies for predicting hospital readmissions in dementia, they outlined contrasting results.Hospital admission aetiologies were found to have more clinical weighting than co-existing medical conditions when predicting hospital readmission in older PLWD [44].Nevertheless, a significantly smaller sample of 203 PLWD participated in this study, which may reflect the difference in comorbidity-related hospital readmissions in the previously mentioned studies, which included larger samples of 50,000 to 2 million PLWD [18,19,49,51].

Discussion
This narrative review provided an overview of some of the psychosocial determinants that contribute towards hospital readmissions in older PLWD, in addition to the known physical determinants.Over half of the publications in this review highlighted psychosocial determinants that are likely to increase the risk of hospital readmissions in dementia [11,17,45,16,46,50,52,[55][56][57].These psychosocial determinants included inadequate hospital discharge planning particularly when PLWD were discharged to their homes [46,50,52], insufficient information sharing of care needs between healthcare staff in hospital and community settings [55], and socioeconomic disadvantages among certain ethnic minority groups [57].Six of the 17 articles in this review outlined the physical determinants that are known to increase the risk of hospital readmission for PLWD, which included living with common long-term conditions such as cardiovascular disease and living with an accumulation of long-term conditions throughout the dementia diagnosis [18,19,44,47,49,51].Consequently, reduced mobility and the functional ability to perform everyday activities such as self-care tasks, are also known to increase hospital readmissions in older PLWD [47].While this review highlighted the elevated risk of hospital readmissions associated with the coexistence of multiple physical conditions, reduced mobility and function, the contribution of frailty in older individuals with dementia was overlooked in the included studies.However, frailty in PLWD is associated with an increased risk of hospital readmissions, as demonstrated by an observational study conducted by Briggs et al. [58].Some articles that highlighted physical determinants of hospital readmissions acknowledged the importance of psychosocial determinants that may increase the risk of rehospitalisation in older PLWD [18,47,51,53].The authors discussed that where common acute conditions may increase the risk of hospital readmissions, these readmissions could also be indicative of problems in the continuity of care, inefficient resource use, and the unrecognised need for special discharge planning in acute care [18,47,51,53].

Psychosocial and physical connection of hospital readmissions in dementia
The frequent use of antipsychotic medication in older PLWD was recognised to explain the interplay between the psychosocial and physical determinants of hospital readmissions [53].Antipsychotic medication is primarily used for psychosis in mental health conditions including schizophrenia and bipolar disorder [59].However, antipsychotic medication was additionally licensed in the 1950s for short-term use to manage behavioural and psychological symptoms of dementia (BPSD), following ineffective non-pharmacological treatments [59][60][61].Our review raises concerns about the frequent use of antipsychotic medication in older PLWD, as they are sensitive to the extrapyramidal side effects which include Parkinsonlike tremors, involuntary muscle contractions and QT prolongation (interference with conduction in the heart) [59,60].These side effects of antipsychotic medication in dementia increase the risk of other common side effects including falls, sedation, and cognitive decline, which may increase the length of hospital stay and consequently accumulate additional care needs [61].Daiello et al. [53] demonstrated the consequences of the side effects that follow repeated use of antipsychotic medication, as older PLWD with 30-day hospital readmissions were more likely to have at least two prescriptions for antipsychotic medication within one year.Even though an association between psychosocial and physical determinants of hospital readmissions in dementia exists with a plausible underlying theory, there is still limited evidence to support this statement.

Fragmented health and social care
This review highlights fragmented care between health and social care professionals leading to poor distribution of care responsibilities, which results in increased rates of hospital readmission for older PLWD [17,18,55].The Global Action Plan for Dementia by the World Health Organization emphasises the need for all countries to shift the focus of care from hospitals towards community-based settings, that integrate health and social care systems to provide evidence-based care for PLWD [62].This pledge was reiterated in the Prime Minister's Challenge on Dementia 2020, where the UK Government committed to improving health and social care provision in the community to reduce avoidable hospital readmissions in PLWD [63].In the UK, access to NHS healthcare is free, whereas access to social care is means-tested and limited [64].This can result in certain populations having difficulty in accessing adequately funded social care, including older PLWD [64].Sir Marmot's review titled Health Inequity in England: The Marmot Review 10 Years On, found increasingly deprived areas in the North, Midlands and Southern coastal towns of England [65].Older PLWD living in these socioeconomically deprived areas do not live in environments that support social connectedness, physical health and activity, or mental stimulation [64,65].
For many individuals living with dementia, adjusting to the evolving circumstances during the Covid-19 pandemic involved limited or no access to in-person community healthcare and social activities.A qualitative study conducted by Giebel et al. [66] showed that multiple lockdowns and temporary closures of routine care resulted in a decline in mental stimulation, physical deterioration and heightened dependency among PLWD.Moreover, family carers experienced a decline in both mental and physical health, as they were compelled to provide caregiving responsibilities that would have typically been handled by paid carers [66].
However, the wider health and social care ramifications of Covid-19 are currently being realised.Since in-person healthcare services reopened, PLWD were found to have more advanced dementia with additional physical and psychological care needs, and increased risk of further hospital admissions [67,68].Digital healthcare was widely implemented to mitigate hospital readmissions such as using smart home devices and telemedicine.Determining the types of technology that are both suitable and safe for PLWD requires further investigation [69,70].

Strengths and limitations
A major strength of this review is that to our knowledge, this is the first narrative review to focus on the psychosocial determinants of hospital readmissions in PLWD.Although hospital readmissions in PLWD have been previously addressed in research, the physical determinants have gained more attention than other determinants of hospital readmissions [11,18,53,71].Our review demonstrated the importance of some of the psychosocial impacts of dementia in addition to the known physical impact.
This review also adopted the methodological framework devised by Arksey and O'Malley [26], to guide a systematic approach and promote scientific rigour.Arksey and O'Malley were the first scholars to develop an internationally recognised framework that follows an iterative process, to clarify the usefulness and methodology of reviews of an exploratory nature.This review also utilised the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) [27], to provide a guided report of the narrative review.
Limitations of this review include that the majority of publications were conducted within Western society.Only two studies in this review were from Japan and Taiwan [18,44], compared to eight studies from the USA [45-47, 49-51, 53, 55].As healthcare systems operate differently around the world, future research should be conducted for non-Western societies with rapidly ageing populations living with dementia.Secondly, it is important to note that the data collected in this review span the period from 1991 to 2019, despite studies being published up to 2023.Hence, such data may not provide a comprehensive reflection of the current understanding of hospital readmissions in PLWD, considering that the data were collected before the onset of the Covid-19 pandemic.Lastly, there was heterogeneity within the studies including different study samples, study aims and outcome measures.Hence, a meta-analysis was not conducted in this review.

Future recommendations for research
Future recommendations for research should highlight the voices of healthcare staff and family carers of older PLWD, within different care settings.This review only managed to obtain the experiences and perceptions of care transitions for PLWD from nursing home staff [55].Although the interviews highlighted problems resulting in 30-day hospital readmissions for older PLWD, there was a lack of varied voices representing dementia care.Many of the publications in this review discuss the barriers of access to care, limited care resources within hospital and community settings, and problems with hospital discharge planning [16,18,46,51,55].However, little is known about why these problems exist.Therefore, future discussions with healthcare staff and family carers involved in dementia care could highlight the underlying issues of hospital readmissions among older PLWD.
Future research should focus on providing evidence to explain the interactions between the psychosocial and physical determinants of hospital readmissions in older PLWD, to address the root cause of this problem.Despite attempting to identify and investigate emerging links between psychosocial and physical determinants, the literature contained a dearth of data to allow us to draw conclusions.One would assume that significant synergistic or at least additive interactions exist between physical and psychosocial factors, perpetuating high rates of hospital readmissions for PLWD.However, this will need to await studies to be specifically designed to answer such important questions.Only by understanding such potential interactions would one be able to deliver a holistic intervention approach to decrease rates of hospital readmissions for PLWD.Unfortunately at this time, there is limited evidence to demonstrate how managing both the psychosocial and physical determinants of dementia can help reduce hospital readmissions in older PLWD.This is to recognise that health outcomes according to each determinant of health are nuanced and complex [72].Nevertheless, effective interventions to help manage these determinants together could support the multi-factorial problem of hospital readmissions for older PLWD.Future research should highlight appropriate approaches to help tackle this problem.
Despite our systematic approach to the literature search, only few psychosocial factors were identified.One can assume that several other psychosocial factors must exist that could have an impact on hospital readmission rates for PLWD.The list of such factors includes but is not limited to loneliness, poverty, education, mental wellbeing, willingness to accept help and family support.Many psychosocial factors have been suspected as potentially being implicated in hospital readmissions in PLWD, which include being an immigrant, male sex, having behavioural symptoms and frequent use of antipsychotic medication [11].Interpersonal factors of dementia care were also highlighted, as living with fewer cohabitants, problems with discharge care transitions, high caregiver stress and inadequate caregiver support were reported to contribute to increased hospital readmissions.Future research needs to assess these and other psychosocial factors individually, in combination with each other as well as the other implicated physical factors.

Conclusion
This review provides insight into how few psychosocial determinants may result in increased hospital readmissions for PLWD.The determinants include inadequate integrated care and insufficient care planning between care settings and healthcare professionals.Future research should try to identify the impact of a myriad of other psychosocial factors and focus on the interaction between the psychosocial and physical determinants, and multidisciplinary interventions across care settings to reduce acute recurrent admissions in dementia.

Table 1 (
continued) a Studies sorted by year of publication, then by surname of first author

Table 2
Identified narrative categories with respective studies